A heat-developable color light-sensitive material is known in the art. For example, heat-developable light-sensitive materials and processes thereof are described in Shashin Kogaku no Kiso (Principle of Photographic Engineering), edition of non-silver salt system photography, published by Corona Co., 1982, pp. 242-255, and U.S. Pat. No. 4,500,626.
Furthermore, a method which comprises the coupling reaction of an oxidation product of a developing agent with a coupler to form a dye image is described in U.S. Pat. Nos. 3,761,270 and 4,021,240. Also, a method which comprises bleaching a photosensitive silver dye to form a positive color image is described in U.S. Pat. No. 4,235,957.
A method has been recently proposed which comprises allowing imagewise release or formation of a diffusible dye by a heat development, and then transferring the diffusible dye to a dye-fixing element. In this method, both negative and positive dye images can be obtained by altering the kind of dye-providing compounds used or the kind of silver halides used. Specifically, this method is described in U.S. Pat. Nos. 4,500,626, 4,483,914, 4,503,137, 4,559,290, JP-A-58-149046 (The term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-60-133449, JP-A-59-218443, JP-A-61-238056, EP-A-220746, EP-A-210660, and JIII Journal of Technical Disclosure 87-6199.
Many methods for obtaining a positive color image by a heat development have been proposed. For example, U.S. Pat. No. 4,559,290 discloses a method which comprises coexisting a reducing agent or a precursor thereof with an oxidized DRR compound having no capability of releasing a dye image, oxidizing the reducing agent depending on the exposure of silver halide by a heat development, and reducing the oxidized DDR compound to release a non-diffusible dye. Further, EP-A-220746 and JIII Journal of Technical Disclosure 87-6199 (vol. 12, No. 22) disclose a heat-developable color light-sensitive material using a compound which releases a nondiffusible dye by a reductive cleavage of N--X bond (wherein X represents an oxygen atom, nitrogen atom or sulfur atom) in the similar mechanism as mentioned above.
In general, conventional color light-sensitive materials have been spectrally sensitized to blue, green and red. In order to record an image data which has been converted to an electrical signal on such a color light-sensitive material, a color CRT (cathode ray tube) is normally used as an exposing light source. However, CRT is unfit to provide a large-sized print.
As writing heads capable of providing a large-sized print, light-emitting diode (LED) and semiconductor laser (LD) have been developed. However, no such writing heads which can perform efficient emission of blue light have been developed.
Accordingly, if LED's are used, it is necessary that three LED's, i.e., near infrared (800 nm) LED, red (670 nm) LED and yellow (570 nm) LED, be combined to provide a light source to which a color light-sensitive material having three layers spectrally sensitized to near infrared, red and yellow ranges, respectively, is exposed. An image recording system having such a mechanism is described in Nikkei New Material, Sep. 14, 1987, pp. 47-57. Some systems have been put into practical use.
Further, JP-A-61-137149 discloses a system which comprises three LD's emitting light of 880 nm, 820 nm and 760 nm in combination to form a light source to which a color light-sensitive material having three light-sensitive layers spectral sensitivity to the respective wavelength ranges to perform recording.
When a multi-layer color light-sensitive material which is adapted to be exposed to three different spectral ranges to develop three colors, i.e., yellow, magenta, and cyan, it is usually an important technique for color reproduction to develop these colors without staining colors. In particular, if LED or LD is used as an exposing light source, the light-sensitive material must be designed to such an extent that the three spectral sensitivities are provided in a narrow spectral range (i.e., from the short wavelength side of red to infrared). Therefore, how the overlap of these spectral sensitivities can be minimized is essential for improving color separatability.
As techniques for securing color separatability, a technique increasing the sensitivity towards the short wavelength side and providing a filter layer has been known as described in U.S. Pat. No. 4,619,892. However, the increase in the sensitivity towards the short wavelength side is disadvantageous because fog is formed and aging stability is deteriorated. Accordingly, in the infrared sensitization, high sensitivity can be hardly attained because of desensitization caused by the addition of a dye or low color sensitization efficiency.
To solve these problems, JP-A-4-146431 and JP-A-5-45828 disclose a color light-sensitive material which comprises a J-band type infrared sensitizing dye having a sharp spectral sensitivity to exhibit a good color separation, a high sensitivity and a good storage stability.
However, the heat-developable color light-sensitive material comprising such a J-band type infrared sensitizing dye is disadvantageous in that the resulting image is liable to a great tint change under some environmental conditions, particularly temperature, during exposure.